TY - JOUR
T1 - A comparative study of shape representation in macaque visual areas V2 and V4
AU - Hegdé, Jay
AU - Van Essen, David C.
N1 - Funding Information:
This work was supported by the National Institute of Health grant EY02091 to DCVE. JH wishes to thank Drs Thomas Albright and Gene Stoner for advice and support during the preparation of this manuscript. We thank Drs Odelia Schwartz, Paul Shrater, and Terrence Sejnowski for helpful discussions, and Drs Leanne Chukoskie, Greg Horwitz, Xin Huang, Bart Krekelberg, and Anja Schlack for useful comments on various drafts of the manuscript, and Susan Danker for assistance with manuscript preparation. Conflict of Interest: None declared.
PY - 2007/5
Y1 - 2007/5
N2 - We compared aspects of shape representation in extrastriate visual areas V2 and V4, which are both implicated in shape processing and belong to different hierarchical levels. We recorded responses of cells in awake, fixating monkeys to matched sets of contour and grating stimuli of low or intermediate complexity. These included simple stimuli (bars and sinusoids) and more complex stimuli (angles, intersections, arcs, and non-Cartesian gratings), all scaled to receptive field size. The responses of cells within each area were substantially modulated by each shape characteristic tested, with substantial overlap between areas by many response measures. Our analyses revealed many clear and reliable differences between areas in terms of the effectiveness of, and response modulation by, various shape characteristics. Grating stimuli were on average more effective than contour stimuli in V2 and V4, but the difference was more pronounced in V4. As a population, V4 showed greater response modulation by some shape characteristics (including simple shape characteristics) and V2 showed greater response modulation by many others (including complex shape characteristics). Recordings from area V1 demonstrated complex shape selectivity in some cells and relatively modest population differences in comparison with V2. Altogether, the representation of 2-dimensional shape characteristics revealed by this analysis varies substantially among the 3 areas. But surprisingly, the differences revealed by our analyses, individually or collectively, do not parallel the stepwise organization of the anatomical hierarchy. Commonalities of visual shape representation across hierarchical levels may reflect the replication of neural circuits used in generating complex shape representations at multiple spatial scales.
AB - We compared aspects of shape representation in extrastriate visual areas V2 and V4, which are both implicated in shape processing and belong to different hierarchical levels. We recorded responses of cells in awake, fixating monkeys to matched sets of contour and grating stimuli of low or intermediate complexity. These included simple stimuli (bars and sinusoids) and more complex stimuli (angles, intersections, arcs, and non-Cartesian gratings), all scaled to receptive field size. The responses of cells within each area were substantially modulated by each shape characteristic tested, with substantial overlap between areas by many response measures. Our analyses revealed many clear and reliable differences between areas in terms of the effectiveness of, and response modulation by, various shape characteristics. Grating stimuli were on average more effective than contour stimuli in V2 and V4, but the difference was more pronounced in V4. As a population, V4 showed greater response modulation by some shape characteristics (including simple shape characteristics) and V2 showed greater response modulation by many others (including complex shape characteristics). Recordings from area V1 demonstrated complex shape selectivity in some cells and relatively modest population differences in comparison with V2. Altogether, the representation of 2-dimensional shape characteristics revealed by this analysis varies substantially among the 3 areas. But surprisingly, the differences revealed by our analyses, individually or collectively, do not parallel the stepwise organization of the anatomical hierarchy. Commonalities of visual shape representation across hierarchical levels may reflect the replication of neural circuits used in generating complex shape representations at multiple spatial scales.
KW - Contours
KW - Extrastriate cortex
KW - Hierarchical processing
KW - Non-Cartesian gratings
KW - Receiver operating characteristic (ROC) analysis
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U2 - 10.1093/cercor/bhl020
DO - 10.1093/cercor/bhl020
M3 - Article
C2 - 16785255
AN - SCOPUS:34247111185
SN - 1047-3211
VL - 17
SP - 1100
EP - 1116
JO - Cerebral Cortex
JF - Cerebral Cortex
IS - 5
ER -